Glaze type · Iron glazes
Tenmoku
Across 206 published recipes: mostly cone 10 and cone 9, fired in reduction and oxidation; Glossy, opaque.
Materials that define it
Share of recipes containing each material, and the typical amount when present. Materials link to their reference pages.
| Material | In recipes | Typical | Half of recipes |
|---|---|---|---|
| Red iron oxide | 91% | 10% | 8–10% |
| Silica | 89% | 22.68% | 16–27% |
| Whiting | 82% | 12% | 9.75–17% |
| Custer feldspar | 37% | 45.5% | 41.27–53.76% |
| EPK | 35% | 10.86% | 7–14% |
| Bentonite | 28% | 2% | 2–2% |
| Kaolin | 24% | 9.55% | 6–12.03% |
| Potash feldspar | 20% | 45.46% | 35–55.53% |
| Ball clay | 18% | 15% | 10–26% |
| Zinc oxide | 16% | 2.4% | 2.19–4% |
| Talc | 14% | 6.33% | 5–8.75% |
| Dolomite | 14% | 7.95% | 6.41–11.88% |
| Gerstley borate | 13% | 12% | 3.1–12.5% |
| Nepheline syenite | 11% | 40% | 18–56.3% |
Typical fired chemistry
Median oxide analysis (weight %) across the recipes that report one, with the interquartile range. Silica and alumina set the melt; the fluxes and colorants make the family.
| Oxide | Median | Half of recipes |
|---|---|---|
| SiO2 | 56.07% | 52.48–58.13% |
| Al2O3 | 10.89% | 10.2–12.08% |
| B2O3 | 2.99% | 1.18–5.24% |
| Na2O | 1.56% | 1.27–2.59% |
| K2O | 4.07% | 2.41–4.94% |
| CaO | 8.21% | 6.4–8.98% |
| Fe2O3 | 8.63% | 7.36–9.4% |
What potters should know
Around 10–15% iron in reduction gives tenmoku; the median iron above sits right there.
Related types
Questions
- What is a Tenmoku glaze?
- In 206 published recipes, Tenmoku glazes are mostly fired to cone 10 and cone 9 in reduction and oxidation, with a Glossy, opaque result. The defining materials are Red iron oxide, Silica, Whiting, Custer feldspar, EPK.
- What cone is Tenmoku fired to?
- The most common cones in published recipes are cone 10 and cone 9; the full distribution is on this page. Atmosphere matters as much as cone for this family: reduction and oxidation.
- What is the typical chemistry of a Tenmoku glaze?
- Median fired analysis: SiO2 56.07%, Al2O3 10.89%, B2O3 2.99%, Na2O 1.56%, K2O 4.07%, CaO 8.21%. Treat these as the centre of a range, not a target — the same family spans different fluxes and cones.
Sources. Every figure is a statistic computed by Claybench over 10,859 glaze recipes compiled from publicly shared community recipe collections (snapshot 2026-02-27); no recipe is reproduced. Colour-chemistry notes are paraphrased from Linda Arbuckle's Ceramic Materials handout.
Colorant and flux notes touch on materials with handling hazards (barium, cobalt, chrome, manganese, lead in historic recipes). Read each material's page and its supplier SDS before mixing; test any food surface.
Claybench checks a glaze against your clay body and cone before it lands on a plan
Recipes, materials, hazards and cone fit — the same reference behind this page, inside the studio planner.